Heretofore, metal cans, glass bottles, or containers or shapes of thermoplastic resin and the like are used as packaging materials for drugs, drinks, foods, chemicals, etc. Above all, containers and shapes of thermoplastic resin excel any others in their lightweightness, formability, packages producibility such as sealability, and cost, and are used most popularly. However, in general, containers and shapes of thermoplastic resin are excellent as packaging materials but have some problems in point of their storability for the contents therein since oxygen penetration through the container wall thereof occurs on a non-negligible order level.
For preventing oxygen penetration from the outside thereof, the containers and the shapes of thermoplastic resin are so planned that the container wall could have a multilayer structure, at least one layer of which is an oxygen barrier layer of polymetaxylylenadipamide (hereinafter referred to as “N-MXD6”), ethylene/vinyl alcohol copolymer, polyacrylonitrile, aluminium foil or the like. However, it is still impossible to fully prevent even slight oxygen from penetrating into the containers from outside, and is also impossible to prevent the contents sensible to oxygen such as beer or the like from being deteriorated by oxygen remaining in the containers.
For removing oxygen from containers, an oxygen absorbent has been used in the past. For example, PTL 1 and PTL 2 describe an oxygen-absorbing multilayer structure and an oxygen-absorbing film with an oxygen absorbent such as iron powder or the like dispersed in resin. PTL 3 describes an oxygen-collecting barrier for packaging capable of absorbing oxygen inside and outside a container formed of a polymer material such as polyamide or the like with a metallic catalyst such as cobalt or the like added thereto. PTL 4 describes a product having an oxygen-scavenging layer that contains an ethylenic unsaturated compound such as polybutadiene or the like and a transition metal catalyst such as cobalt or the like, and an oxygen-blocking layer of polyamide or the like.